(1) Field of the Technology
The present technology relates to a toner feed unit used in conveying toner to a predetermined position and an image forming apparatus equipped with this.
(2) Description of the Prior Art
The electrophotographic image forming apparatus can form images of high image quality with simple control in a short time and it also enables easy maintenance and management, so that it has been widely used as the copier, printer, facsimile machine and the like, for instance. The electrophotographic image forming apparatus (which will be referred to hereinbelow as simply “image forming apparatus”), includes, for example, a photoreceptor, a charging device, an exposure device, a developing device, a transfer device and a fusing device. The photoreceptor has a photosensitive layer on the surface thereof, which is electrified at a predetermined surface potential by the charging device. The exposure device emits signal light in accordance with image information onto the photoreceptor surface that has been electrified to form an electrostatic latent image. The developing device supplies toner to the electrostatic latent image on the photoreceptor surface to develop it into a toner image. The transfer device transfers the toner image from the photoreceptor surface to a recording medium. The fusing device includes, for example, a fusing roller incorporating a heater and a pressing roller put in press-contact with the fusing roller, and leads the recording medium having an unfused toner image thereon into the contact nip between the fusing roller and pressing roller to fuse and fix the toner image to the recording medium. In this way, the image is printed on the recording medium.
The developing device includes a developing roller arranged opposing the photoreceptor that is formed with an electrostatic latent image while rotating, and a developing vessel for holding a developer. The developing device conveys the developer inside the developing vessel to the photoreceptor side by means of the developing roller to thereby develop the electrostatic latent image on the photoreceptor. At this time, when the developer is a dual-component developer made of a toner and a carrier, only the toner is used and consumed for development while the carrier is left inside the developing vessel. The consumed amount of toner is supplied from a toner cartridge or toner hopper to the developing vessel through a toner feed unit.
There are known toner feed unit configurations which are constructed such that toner is prevented from dropping when the developing vessel is removed from the interior of the image forming apparatus to replace the developer. For example, in the image forming apparatus disclosed in patent document 1 (Japanese Patent Application Laid-open 2007-78848), an openable and closable shutter is provided in the supply port of the toner supply unit such that the shutter is closed by operating a lever that is in linkage with the shutter when the developing vessel is taken out from the image forming apparatus, whereas the shutter is opened when the developer vessel is fitted to the predetermined position in the image forming apparatus.
However, the above method suffers the problem that toner adheres to the outside surface of the shutter and the adhering toner falls and scatters.